A typical data communication apparatus that exchanges data traffic with network elements has working ports normally used to handle the data traffic and a protection port to which the data traffic can be switched if one or more of the working ports fail. Protection switching is handled by a protection switching functional element which receives a protection switch request, evaluates its priority, determines if protection may proceed based on network and local conditions, negotiates protection switching with the affected network element and coordinates the movement of data traffic.
Generally, existing protection switching schemes are limited to the 1:Q mode where a single protection line or channel is available to Q working lines or channels. The drawback of this arrangement resides in the limited protection available in the case of failures over multiple working lines or channels. When a working line or channel fails, the data traffic is switched to the protection line or channel. However, if a second working line or channel fails, no additional protection line or channel is available. If the second working line or channel carries higher priority data traffic than the first working line or channel, then the data traffic from the second working line or channel will be switched over the protection line, and the data traffic from the first working line or channel will be dropped.
Against this background there clearly appears that a need exists in the industry to provide a protection switching scheme that will increase the level of protection beyond the 1:Q.